Technical Field
The present invention relates to an optical data processing technique, and specifically relates to a technique for integrally processing three-dimensional data obtained from different points of view.
Background Art
A technique in which a three-dimensional position of an object to be measured is obtained as a large number of point cloud position data by irradiating a laser beam onto object to be measured while scanning, and a three-dimensional shape of the object to be measured is calculated by this point cloud position data, has been known (see Patent Document 1). In the point cloud position data, a two-dimensional image and three-dimensional coordinates are combined. That is, in the point cloud position data, data of a two-dimensional image of an object, multiple measured points (point cloud) corresponding to this two-dimensional image, and position in three-dimensional space (three-dimensional coordinates) of these multiple measured points are related. By using the point cloud position data, a three-dimensional model in which a surface configuration of the object is duplicated by a series of points can be obtained. In addition, since each three-dimensional coordinate is obvious, relative positional relationship in three-dimensional space among the points can be understood; therefore, a processing revolving around the three-dimensional model image displayed and a processing switching to an image seen from a different viewpoint can be realized.
In the case in which the point cloud position data is obtained from one viewpoint, point cloud position data of a part in which a shadow is formed by a shape of the object to be measured or an obstruction when it is viewed from the viewpoint, cannot be obtained. This phenomenon is called occlusion, and this shadow part is called an occlusion portion and an occlusion part. There is a problem in which occlusion is generated by flickering images of passersby, passing vehicles, trees, etc.
As an approach for solving the problem, Patent Document 2 discloses a method in which in addition to a basic acquisition of the point cloud position data, the occlusion part is photographed from different viewpoints and the relationship between this photographic image and the above basic point cloud position data is determined, so as to compensate the point cloud position data of the occlusion part.
Patent Document 1 is Japanese Unexamined Patent Application Publication Laid-open No. 2012-8867. Patent Document 2 is Japanese Unexamined Patent Application Laid-open No. 2008-82707.
The point cloud position data consists of tens of thousands of points to hundreds of millions of points, and positioning of the point cloud position data and the photographic image is required. This processing is complicated, and required processing time is long. As a method of this positioning, a technique in which multiple targets are previously adhered to the object to be measured, so that the correspondence relationship between the point cloud position data and the feature point in the photographic image is clear, and the point cloud position data and the feature point in the photographic image are positioned based on the multiple targets, can be used. However, in this technique, it is necessary to adhere the targets to the object to be measured, and for example, the targets cannot be simply adhered when the object to be measured is a tall building, etc.
In addition, a method in which the matching between data is carried out by using software can also be used. However, there are problems in that a matching error is large, a required processing time is too long, and a large burden is applied to a calculating device. In view of such circumstances, an object of the present invention is to provide a technique in which processing for specifying a correspondence relationship of feature points between two sets of optical data can be carried out with high precision and extremely efficiently.